If you've ever tried to delete or use a file but gotten an error saying it was "in use" by another program—even if you've already closed it—OpenFilesView will help you easily solve the problem by letting you close the locked file from a menu.

OpenFilesView is one of those little portable apps that's great to keep around on the occasions you run into this error (which for me, frankly, is more often than I'd like). It'll show you a list of all open and locked files in the system, so you can find the offending file handle and close it—or kill the entire process behind it, freeing you up to go on with your work without restarting. It's simple, and may not be something you need every day, but it can save you a lot of hair pulling when this common problem arises.

OpenFilesView is a free download for Windows only. Note that there's a 32-bit and a 64-bit version; you'll have to grab the one that matches your system type. The 64-bit version requires you to turn on Driver Signing Test Mode, which you can turn off via the OpenFilesView help menu.